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Abstract:

A heat exchanger of the single circuit type, to be coupled to a fluid
circulation circuit and comprising: an upper tubular head element and a
lower tubular head element horizontally arranged and which are each
provided with a nozzle and through slots provided in an inner
longitudinal wall portion; and a plurality of vertically disposed fluid
conduction tubes, each internally defining a plurality of longitudinal
microchannels. The opposite ends of the fluid conduction tubes are
affixed to the inner longitudinal wall portion of the upper tubular head
element and lower tubular head element, respectively, so as to
communicate the ends of the microchannels of each tube with a through
slot of the respective tubular head element and, thus, the fluid
conduction tubes with the interior of the upper tubular head element and
lower tubular head element.

Claims:

1. A heat exchanger of the single circuit type, to be coupled to a fluid
circulation circuit, comprises: an upper tubular head element and a lower
tubular head element which are horizontally arranged and have closed
ends, each tubular head element being provided with a nozzle for
connection to the fluid circulation circuit, and with a plurality of
through slots provided in an inner longitudinal wall portion of the
respective tubular head element and which are transversal to the
longitudinal axis of the tubular head element; and a plurality of fluid
conduction tubes, of substantially elongated rectangular cross-section,
vertically arranged side-by-side, each fluid conduction tube internally
defining a plurality of longitudinal microchannels with open ends, the
opposite ends of said fluid conduction tubes being affixed against the
inner longitudinal wall portion of the upper tubular head element and
lower tubular head element, respectively, so as to tightly communicate
the ends of the microchannels of each fluid conduction tube with a
through slot of the upper tubular head element and lower tubular head
element, respectively, and thus the fluid conduction tubes with the
interior of the upper tubular head element and lower tubular head
element.

2. The heat exchanger, as set forth in claim 1, wherein the upper tubular
head element and lower tubular head element present a rectangular cross
section.

3. The heat exchanger, as set forth in claim 2, wherein the through slots
present an elongated rectangular contour, similar to and slightly smaller
than that of the fluid conduction tubes.

4. The heat exchanger, as set forth in claim 3, wherein the through slots
are arranged side-by-side, each extending substantially over the whole
width of the inner longitudinal wall of the respective upper tubular head
element and lower tubular head element.

5. The heat exchanger, as set forth in claim 2, wherein the through slots
present an elongated rectangular contour, similar to and slightly smaller
than that of the fluid conduction tubes.

6. The heat exchanger, as set forth in claim 1, wherein the nozzle is
arranged in one of the closed ends of the upper tubular head element and
lower tubular head element.

7. The heat exchanger, as set forth in claim 1, wherein the fluid
conduction tubes have opposite end longitudinal edges in convex arc.

8. The heat exchanger, as set forth in claim 1, wherein the fluid
conduction tubes incorporate small projecting side fins extended along at
least a substantial part of the height of the fluid conduction tubes.

[0003]The present invention refers to a heat exchanger of the single
circuit type to be used as a condenser or as an evaporator, in diverse
applications, particularly in air conditioner appliances, aiming to
facilitate the manufacture and to improve the heat exchange efficiency.

[0004]2. Prior Art

[0005]Nowadays, the heat exchangers manufactured with fluid conduction
tubes of oval flat section, containing microchannels, are horizontally
arranged with corrugated fins, being coupled to the vertically arranged
head elements, at the side ends of the fluid conduction tubes, which form
more than one circuit or are manufactured in the coil type configuration.

[0006]This type of heat exchanger assembly, besides being of high
industrial complexity, has the limitation of not being able to work as an
evaporator, since the oval flat fluid conduction tubes with microchannels
have a flattened form and are mounted with corrugated fins, retaining the
water condensed from air moisture therebetween, impairing the operation
of the heat exchanger and making unfeasible its application as an
evaporator.

[0007]These heat exchangers also have high resistance to the dragging of
refrigerant fluid condensed in its interior, provoking high load losses
in the refrigerating circuits, and demanding a higher power from the
compression equipment.

SUMMARY OF THE INVENTION

[0008]As a function of the inconveniences mentioned above and regarding
the known constructive solutions for the heat exchangers of the
above-considered type, the present invention has the object of providing
a heat exchanger of the single circuit type, which is easy to construct
and which presents more versatility in order to be used as a condenser
and as an evaporator, improving the heat exchange efficiency in any of
said applications, by using the same basic elements defined by tubular
head elements that are coupled to and communicate with the ends of a
plurality of fluid conduction tubes.

[0009]The object above is attained by the provision of a heat exchanger of
the single circuit type, to be coupled to a fluid circulation circuit and
comprising: an upper tubular head element and a lower tubular head
element, which are horizontally arranged and have closed ends, each
tubular head element being provided with a nozzle for connection to the
fluid circulation circuit, and a plurality of through slots provided in
an inner longitudinal wall portion of the respective tubular head element
and which are transversal to the longitudinal axis of the tubular head
element; and a plurality of fluid conduction tubes of substantially
elongated rectangular cross-section and vertically arranged side-by-side,
each fluid conduction tube internally defining a plurality of
longitudinal microchannels with open ends, the opposite ends of said
fluid conduction tubes being affixed against the inner longitudinal wall
portion of the upper and lower tubular head elements, respectively, so as
to tightly communicate the ends of the microchannels of each fluid
conduction tube with a through slot of the upper and lower tubular head
elements, respectively, and thus the fluid conduction tubes with the
interior of the upper and lower tubular head elements.

[0010]The construction proposed herein improves the heat efficiency of the
heat exchanger due to the arrangement and to the increase of the number
of fluid conduction tubes in the same area and to the reduction of the
load loss of the refrigerant circuit, as a consequence of the single
unidirectional circuit through the fluid conduction tubes, i.e., without
changing direction and also due to the fact that the condensed
refrigerant flows directly downwards, when the heat exchanger operates as
a condenser, efficiently separating the gaseous part from the liquid part
and further permitting the refrigerant fluid, evaporated in the gaseous
state, to flow directly upwardly, when the heat exchanger operates as an
evaporator, also efficiently separating the phases of gas+liquid mixture
from the saturated or superheated gas. This arrangement of fluid
conduction tubes in the vertical position can be applied to condensers
and evaporators of vapor-compression refrigerating and/or heating
systems, since, in the case of the application as an evaporator, all the
water condensed at the surface of the tubes will flow by gravity, thus
leaving the surface free for a more effective heat exchange.

[0011]The present constructive solution further contributes to a better
efficiency of the ventilation system, mainly when applied to forced
ventilation systems, since it has less resistance to air passage, thus
contributing to reduce the dimensions and the power required for the
motor of the air impeller, which is generally defined by a fan.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]The invention will be described below, with reference to the
enclosed drawings, given by way of examples of possible embodiments of
the present heat exchanger and in which:

[0013]FIG. 1 represents a front top perspective view of the heat
exchanger;

[0014]FIG. 2 represents a front view of the heat exchanger of FIG. 1;

[0015]FIG. 2A represents an enlarged detail view of the lower end of the
heat exchanger of FIGS. 1 and 2, taken according to the limits defined by
the circle "A" illustrated in FIG. 2;

[0016]FIG. 3 represents an elevation view of the right side of the heat
exchanger of FIGS. 1-2A;

[0017]FIG. 4 represents, simultaneously, a top plan view and a lower plan
view of the inner longitudinal walls of the lower and upper tubular head
elements, respectively, of the heat exchanger of FIGS. 1-3, deprived of
the fluid conduction tubes;

[0018]FIG. 4A represents an enlarged detailed view of an end of the lower
and upper tubular head elements of the heat exchanger of FIGS. 1-4, taken
according to the limits defined by the circle "B" illustrated in FIG. 4;

[0019]FIG. 5 represents an enlarged cross sectional view of the fluid
conduction tube of the heat exchanger of FIGS. 1-4A; and

[0020]FIG. 6 represents an enlarged cross sectional view of a constructive
variant for the fluid conduction tube of the heat exchanger of the
previous figures.

DETAILED DESCRIPTION OF THE INVENTION

[0021]As already previously mentioned and illustrated in the enclosed
drawings, the invention refers to the construction of a heat exchanger to
be used as a condenser or as an evaporator in several applications,
particularly in air conditioner appliances, said heat exchanger being of
the single circuit type.

[0022]According to the present invention, the heat exchanger comprises an
upper tubular head element 10 and a lower tubular head element 20,
constructed in any adequate material, such as for example, carbon steel,
stainless steel, thermoplastic material, etc., and which are horizontally
arranged and have their ends closed, so that each tubular head element
defines a tube extension whose cross section can vary according to the
heat exchanger project. In the embodiment illustrated in the drawings,
the upper tubular head element 10 and the lower tubular head element 20
present a rectangular cross section, having an inner longitudinal wall
10a, 20a turned to the heat exchanger structure and which, in the case of
the embodiment of rectangular section, defines a flat surface, also of
rectangular contour. The upper tubular head element 10 and the lower
tubular head element 20 each further presents, in said construction of
rectangular cross section, an outer longitudinal wall 10b, 20b, turned
outwardly from the heat exchanger body or structure.

[0023]Each upper tubular head element 10 and lower tubular head element 20
is provided, generally in one of its closed ends, with a nozzle 11, 21,
for connecting said upper tubular head element 10 and lower tubular head
element 20 to a fluid circulation circuit with which the heat exchanger
is operatively associated. These nozzles 11, 21 can present different
constructions that are well known in the prior art, its particular
construction not being a relevant aspect to the object of the present
invention.

[0024]As illustrated in the enclosed drawings, each upper tubular head
element 10 and lower tubular head element 20 presents, in an inner
longitudinal wall portion 10a, 20a, a plurality of through slots 12, 22
arranged transversal to the longitudinal axis of the respective tubular
head element, said through slots 12, 22 generally presenting an elongated
rectangular contour that is similar to and slightly smaller than that of
the fluid conduction tubes 30. The through slots 12, 22 are arranged
side-by-side, each extended substantially over the whole width of the
inner longitudinal wall 10a, 20a of the respective upper tubular head
element 10 and lower tubular head element 20. In case of constructing the
tubular head elements with a rectangular cross section, the through slots
12, 22 present an extension which substantially corresponds to the width
of the inner longitudinal wall of the tubular head element.

[0025]The present heat exchanger further comprises a plurality of fluid
conduction tubes 30 presenting a substantially elongated rectangular
cross-section and being vertically arranged side-by-side. Each fluid
conduction tube 30 is constructed so as to internally define a plurality
of longitudinal microchannels 31 with open ends coinciding with the ends
of the respective fluid conduction tube 30, the opposite ends of said
fluid conduction tubes 30 being affixed, by any adequate process, such as
brazing, against the inner longitudinal wall portion 10a, 20a of the
upper tubular head element 10 and lower tubular head element 20,
respectively, so as to allow the occurrence of a tight fluid
communication between the ends of the microchannels 31, of each fluid
conduction tube 30, with a through slot 12, 22 of the upper tubular head
element 10 and lower tubular head element 20, respectively and,
consequently, between the fluid conduction tubes 30 and the interior of
the upper tubular head element 10 and lower tubular head element 20
through the through slots 12, 22.

[0026]As illustrated, the present construction allows the fluid conduction
tubes 30 to be arranged side-by-side, with its longitudinal extension
parallel to the direction of the airflow passing through the spacings
defined between said fluid conduction tubes 30 and along their side
walls, thereby facilitating the airflow through the heat exchanger,
without the existence of elements which cause undesired load loss to the
through airflow. In order to facilitate airflow, the fluid conduction
tubes 30 can be constructed with their opposite end longitudinal edges 32
tapered or simply configured in a convex arc, as illustrated in FIGS. 5
and 6 of the enclosed drawings. The fluid conduction tubes 30 can be
constructed with externally smooth side walls or also incorporating small
projecting side fins 33, extending along at least a substantial part of
the height of the fluid conduction tubes 30. These small projecting side
fins 33 are formed in the material that constitutes the respective fluid
conduction tubes 30, considerably facilitating the construction of said
elements and allowing an effective increase in its heat exchange outer
surface area.

[0027]It should be understood that, in the case of providing fluid
conduction tubes 30, such as in the construction illustrated in FIG. 6,
the spacing between each pair of adjacent fluid conduction tubes 30 is
designed to define an adequate distance between the free ends of the
confronting small projecting side fins 33, so as not to impair the heat
exchange airflow passing between said fluid conduction tubes 30 of the
heat exchanger.

[0028]While only two possible constructive forms of the present heat
exchanger have been illustrated herein, it should be understood that
alterations can be made in the form and physical arrangement of the
elements, without departing from the constructive concept defined in the
claims that accompany the present specification.